1. Field
The present invention is concerned with catalysts, particularly those useful in hydroconversion processes, more preferably hydrocracking processes, a method of manufacturing the catalysts, and a process for using the catalysts.
2. Prior Art
The prior art abounds with methods for the production of catalysts comprising a metal associated with the surface of a porous inorganic oxide support. In accordance with the prior art, said catalyst can be produced, for example, by impregnating a preformed inorganic oxide carrier with the metal or by coprecipitating the metal as an oxide or hydroxide along with the materials forming the porous inorganic oxide support; for example, the pH of a solution containing dissolved silica, alumina and palladium can be adjusted to the point where the silica and alumina coprecipitate and the palladium is chemisorbed to a limited extent onto the resulting silica-alumina coprecipitate, said palladium being primarily in the form of soluble palladium hydroxide and/or soluble palladium salts. The palladium does not coprecipitate along with the silica and alumina since the palladium cation and, more particularly, palladium hydroxide, are soluble at pH's within the range that silica and alumina coprecipitate.
U.S. Pat. Nos. 1,280,314, 1,282,296 and 1,282,297 teach impregnating a powder with nickel by precipitation with a nitrogenous organic colloid.
U.S. Pat. No. 2,662,861 teaches preparing: (1) a slurry of alumina, washing it, adding a promoter, bubbling hydrogen sulfide through (2) a solution of chloroplatinic acid hexahydrate, mixing (1) and (2) together and drying to form a catalyst.
U.S. Pat. No. 2,898,305 teaches mixing silica in a slurry form with an insoluble inorganic compound, drying and calcining.
U.S. Pat. No. 2,688,603 teaches catalyst preparation by distributing an organic compound containing a potentially catalytically active metal on the surface of a suitable support and decomposing the precursor to remove the organic portion of the molecule.
U.S. Pat. No. 3,210,296 teaches impregnating an inorganic oxide support by use of a noble metal compound dissolved in an alcohol, ether, aldehyde, ketone or mixture thereof.
It has been surprisingly discovered that when catalysts comprising a metal associated with a porous inorganic oxide support are prepared by the method of the present invention, a larger proportion of the metal, preferably palladium, attempted to be incorporated into said catalysts is actually incorporated therein than is obtained by the prior art coprecipitation-plus-chemisorption method of catalyst preparation. It has also been surprisingly discovered that when a catalyst is prepared according to the present invention the resulting catalyst has higher catalytic hydrogenation stability than do prior art catalysts. It is believed that the higher catalytic hydrogenation stability found for the catalyst prepared in accordance with the present invention is the result of the attainment of a more uniform dispersion of the metal upon the surface of the porous inorganic oxide support than is obtained by the prior art methods of catalyst preparation.